Two-component preparations containing epoxy compounds

ABSTRACT

The invention relates to two-component preparations comprising components (I) and (II), wherein at least one component comprises epoxy compounds and the preparations cure by cationic polymerization, initiated by Lewis and/or Brönsted acids, after mixing of the two components, the preparations comprising the Lewis and/or Brönsted acids in the form of precursor compounds which are suitable for the formation of Lewis and/or Brönsted acids.

This application is the national phase under 35 U.S.C. §371 of PCTInternational Application No. PCT/EP00/02388 which has an Internationalfiling date of Mar. 17, 2000, which designated the United States ofAmerica.

The invention relates to two-component preparations comprising epoxycompounds, in particular for the preparation of dental compositions. Theinvention particularly relates to two-component dental compositionswhich comprise epoxy compounds and are cured by cationic polymerization.

An important parameter of multi-component dental compositions is theirprocessing time. This is understood as meaning the time from the startof setting after mixing of the component to curing of the composition.After mixing the components of the dental composition, the user requiresan exactly defined period of time in which he can handle the compositionwithout problems. Directly after this period of time the compositionshould harden within the shortest time. A slow solidifying of thecomposition during processing or working is intolerable for the user.

Various systems which attempt to adjust the course of setting of acuring dental composition are known from the prior art.

DE-A-197 53 461 describes, for example, storage-stable cationicallypolymerizing preparations in which soluble and/or finely dividedalkaline earth metal and/or alkali metal compounds allow adjustment ofthe course of setting. In the case of two-component formulations, theinitiator system described there can comprise, inter alia, free Lewis orBrönsted acids. A disadvantage of these preparations is that they allowonly a very limited period of time for adjustment of the start ofsetting, and in addition if the concentration of alkaline earth oralkali metals is increased for the purpose of extending the settingrange, they severely delay the end of setting and severely adverselyimpair the mechanical properties.

DE-A-197 42 980 indeed describes in principle cationically polymerizablecompositions, but these are based on ROMP oligomers or polymers, itbeing possible for epoxy-functional comonomers to be added to thecompositions. Free Lewis or Brönsted acids are employed in the catalystsystem mentioned. A disadvantage of this system is the fact that thecourse of setting cannot be adjusted. After the start of thepolymerization, this starts to proceed and leads to a hard material witha low volume shrinkage within an extremely short time.

DE-A-195 02 751 describes photocurable model materials for dentistry inwhich Lewis acids can be formed by a suitable light source. Photocurablematerials indeed in principle have a processing time of any desiredlength, but in practice this property would take effect only in a darkroom. In the dental sector, however, work is carried out in withoutprotection in daylight or under an intense artificial light source,which lead to a gradual solidifying of the dental material, as a resultof which these initiation systems are not suitable for the preparationof dental materials with a widely adjustable processing time.

Further polymerizable compositions based on epoxides with Lewis orBrönsted acids in free or reactive form as the catalyst or initiatorsystem are known from DE-A-196 48 283. A disadvantage of thesecompositions in turn is that the setting characteristics cannot beadjusted.

The invention is based on the object of providing dental compositionswhich do not have the disadvantages from the prior art.

This object is achieved by two-component preparations, wherein at leastone component comprises epoxy compounds and the preparations cure bycationic polymerization, initiated by Lewis and/or Brönsted acids, aftermixing of the two components, the preparations comprising the Lewisand/or Brönsted acids in the form of precursor compounds which aresuitable for the formation of Lewis and/or Brönsted acids and which areformed by chemical reaction during or after mixing of the components.

The advantages of the dental compositions prepared from the preparationsaccording to the invention lie in the exact adjustability of theprocessing time and in the outstanding physical values of the cureddental compositions.

In particular, when the dental compositions are used as model materialsin dentistry for the production of working models, further advantagesare found: Compared with gypsum, the compositions according to theinvention show increased mechanical values, such as abrasion resistance,tensile strength and compressive strength. The detail reproduction offine contours and grooves and the dimensional accuracy, which is largelyinfluenced by the lowest possible polymerization shrinkage, are alsoconsiderably better. Compared with model materials known to date whichare based on plastics and are distinguished by a rather cumbersomehandling and/or by too long a setting phase compared with gypsum, thedental compositions according to the invention can be mixedautomatically and the setting phase can be adjusted in an outstandingmanner. The end of the setting phase determines the earliest possiblepoint in time at which the model can be removed from the mould andworked further.

The preparations are also suitable for other dental applications wherelow shrinkage is an advantage, for example as materials for theproduction of temporary crowns and bridges and fixing cements.

The preparations according to the invention comprise two components (I)and (II).

The epoxy compounds and the Lewis and/or Brönsted acids in the form ofcompounds which are capable of the formation of Lewis and/or Brönstedacids and do not react with the epoxy compounds can be present incomponent (I) and/or in component (II) in any desired distribution.

Dental compositions obtained from the preparations according to theinvention comprise, distributed over components (I) and (II), thefollowing constituents:

(A) 10 to 80 wt. %, preferably 10 to 60 wt. %, of epoxy compounds,

(B) 0.01 to 20 wt. %, preferably 0.1 to 10 wt. %, of compounds which arecapable of formation of Lewis or Brönsted acids, and optionally freeLewis and/or Brönsted acids,

(C) 10 to 89.99 wt. %, preferably 30 to 89.99 wt. %, of diluents,

(D) 0 to 79.99 wt. %, preferably 15 to 59.99 wt. %, of modifiers.

Epoxy compounds according to constituent (A) can be cycloaliphaticand/or aromatic and/or aliphatic epoxy compounds with at least twoand/or at least four epoxy groups.

Cycloaliphatic epoxides can be, for example, the epoxides known fromDE-A-196 48 283, which correspond to the following general formulae:

in which the symbols have the following meanings:

Z an aliphatic, cycloaliphatic or aromatic radical having 0 to 22,preferably 0 to 18 C atoms, or a combination of these radicals, it beingpossible for one or more C atoms to be replaced by O, C═O, —O(C═O)—,SiR₂ and/or NR, wherein R is an aliphatic radical having 1 to 7 C atoms,it being possible for one or more C atoms to be replaced by O, C═Oand/or —O(C═O)—,

A an aliphatic, cycloaliphatic or aromatic radical having 1 to 18,preferably 1 to 15 C atoms or a combination of these radicals, it beingpossible for one or more C atoms to be replaced by O, C═O, —O(C═O)—,SiR₂ and/or NR, wherein R is an aliphatic radical having 1 to 7 C atoms,in which one or more C atoms can be replaced by O, C═O and/or —O(C═O)—,

B¹, B², D, E independently of one another, an H atom or an aliphaticradical having 1 to 9, preferably 1 to 7 C atoms, it being possible forone or more C atoms to be replaced by O, C═O, —O(C═O)—, SiR₂ and/or NR,wherein R is an aliphatic radical having 1 to 7 C atoms, in which one ormore C atoms can be replaced by O, C═O and/or ═O(C═O)—,

X CH₂, S or O,

n 2 to 7, preferably 2 to 5,

m 1 to 10, preferably 1 to 7,

p 1 to 5, preferably 1 to 4, and

q 1 to 5, preferably 1 to 4.

Low-viscosity epoxides such as are described in DE-A-196 48 283 can alsobe employed.

The epoxides known from U.S. Pat. Nos. 2,716,123, 2,985,667, 2,750,395,2,863,881, 3,187,018, 5,085,124, EP-A-0 449 027 and EP-A-0 574 265 arealso suitable, in particular epoxides of the following structuralformulae

Combinations of aliphatic, cycloaliphatic or aromatic epoxides arepossible. Cycloaliphatic epoxy compounds with at least two epoxy groups,cycloaliphatic epoxy compounds with at least four epoxy groups or thecombination of cycloaliphatic epoxy compounds with two epoxy groups andcycloaliphatic epoxy compounds with at least four epoxy groups arepreferably employed.

The Lewis and/or Brönsted acids according to constituent (B) are formedby chemical reactions of selected constituents of the two componentsduring or after mixing thereof. Free Lewis and/or Brönsted acids such asare known from conventional systems can also be employed.

In the case where free Lewis or Brönsted acids are additionally used, ithas proved expedient to add the acids to that component which comprisesno epoxy compounds. Where appropriate, to adjust the processing time itis expedient also to employ the substances for delaying cationicpolymerization known from DE-A-197 53 461—which has not yet beenpublished at the time of this Application.

Examples of free acids which may be mentioned are: BF₃ or adductsthereof, such as, for example, BF₃∃THF, BF₃∃Et₂O, AlCl₃, FeCl₃, HPF₆,HAsF₆, HSbF₆ and HBF₄.

Both components of the dental compositions according to the inventioncan additionally comprise certain contents of so-called photoinitiatorswhich form Brönsted or Lewis acids when irradiated with light of thewavelength range from 200 to 650 nm. Typical classes of compounds forthese photoinitiators are onium salts, such as diazonium, sulphonium,iodonium and ferrocenium salts with complex anions of lownucleophilicity. These include, for example, diazonium compounds (U.S.Pat. No. 3,205,157), sulphonium compounds (U.S. Pat. No. 4,173,476) andiodonium compounds (U.S. Pat. Nos. 4,264,703, 4,394,493). In theexamples mentioned, instructions are given to use ultraviolet light.

Derivatives of cyclopentadienyl-iron-arene complexes (EP-A-0 094 915,WO-96/03453, EP-A-0 661 324) can also be used. It is also possible toadd α-dicarbonyl compounds, for example camphorquinone, which act assensitizers in the visible range. Combined preparations ofcamphorquinone and iodonium compounds are known from U.S. Pat. Nos.5,554,676 and 4,828,583.

To produce the Brönsted and/or Lewis acids, the components comprisingphotoinitiators are irradiated, before mixing, by lamps which emit lightof the required wavelength range.

The photoinitiators are preferably employed in a component whichcomprises no epoxy compounds.

The Brönsted and/or Lewis acids are produced by selected constituentswhich are stored separately in the two components and which reactchemically with one another during or after mixing of the twocomponents.

Typical examples of those reactions which can lead to the acidsnecessary for initiation of the polymerization of epoxy compounds areredox reactions using bisaryliodonium salts, reducing agents and coppercomplexes, and the dehalogenation of alkyl halides assisted by metalsalts.

In the case of these latent initiation systems, it is possible to addthe particular reaction partner both to the components comprising epoxycompounds and to the component which comprises no epoxy compounds.

In general, the distribution of the constituents of the latentinitiation systems over the two components is undertaken such thatpremature polymerization of the epoxy compounds during storage of thetwo-component materials is reliably avoided.

This object is achieved, for example, by using components which cannotbe polymerized by acids and which comprise the particularly criticalconstituent of the particular latent initiation system.

In the case of the formation of acids by redox reactions frombisaryliodonium salts, reducing agents and copper compounds, forexample, it has thus proved expedient to store the bisaryliodonium saltsand the reducing agents in a component which comprises no epoxycompounds. A further component then comprises the copper compoundstogether with the epoxy compounds.

The iodonium salts are present in the components to the extent of 0.01to 20 wt. %, preferably 0.2 to 10 wt. %, based on the weight of themixed material, the reducing agents also necessary are present to theextent of 0.01 to 10 wt. %, preferably 0.05 to 5 wt. %, based on theweight of the mixed material, and the copper compounds are present tothe extent of 0.005 to 10 wt. %, preferably 0.01 to 5 wt. %, based onthe weight of the mixed material.

The bisaryliodonium compounds, for example, which are known from U.S.Pat. Nos. 4,225,691 and 4,238,587 are suitable. Methods for thepreparation of further diaryliodonium compounds are known from F. M.Beringer, R. A. Falk, M. Karmal, J. Lillien, G. Masullo, M. Mausner, E.Sommers, J. Am. Chem. Soc., 81, 342 (1958) and I. Mason, Nature, 139,150 (1937).

Diaryliodonium compounds, which are known, inter alia, from DE-A-197 36471, are particularly preferred. They have the following structure:

 [((R¹)_(a)Ar¹)—I—(Ar²(R²)_(b))]⁺Y⁻

Ar¹ and Ar² independently of one another can be different, substitutedor unsubstituted, fused or non-fused aromatic systems having 4 to 20 Catoms, such as, for example, phenyl, tolyl, cumyl, anisyl, chlorophenyl,nitrophenyl, naphthyl, thienyl, furanyl and pyrazolyl, wherein R¹ and R²are identical or different and independently of one another denote an Hatom, an aliphatic radical having 1 to 19, preferably 1 to 9 C atoms, itbeing possible for one or more C atoms to be replaced by O, C═O,—O(C═O)—, F, Cl, Br, SiR³ ₃ and/or NR³ ₂, wherein R³ is an aliphaticradical having 1 to 7 C atoms, in which one or more C atoms can bereplaced by O, C═O and/or —O(C═O)—, and a and b independently of oneanother can be 1 to 5. The aromatics Ar¹ and Ar² can be bonded to oneanother via R¹ and/or R².

The counter-anion Y⁻ is an anion of low nucleophilicity of the followingstructure:

K_(x)L_(y) ⁻

wherein K is an element of main group IIII, V or VII, such as B, Al, P,Sb, As or I, and x can assume numerical values from 1 to 4. The Lindependently of one another denote aromatic, aliphatic, araliphatic orcycloaliphatic radicals having 1 to 25 C atoms, in which one or more Catoms can be substituted by F, Cl, Br or I, and y can assume numericalvalues from 0 to 6.

Preferred radicals L are pentafluorophenyl, tetrafluorophenyl,trifluorophenyl, fluorophenyl, phenyl, 4-trifluoromethylphenyl,3,5-bis(trifluoromethyl)phenyl, 2,4,6-tris(trifluoromethyl)phenyl,fluorine and iodine.

Particularly preferred counter-anions Y⁻ are PF₆ ⁻, AsF₆ ⁻, SbF₆ ⁻,B(C₆F₅)₄ ⁻ and BF₄ ⁻.

Further diaryliodonium compounds are also described, for example, inU.S. Pat. No. 4,246,703.

Particularly suitable diaryliodonium compounds are:

diphenyliodonium tetrafluoroborate

diphenyliodonium hexafluorophosphate

diphenyliodonium hexafluoroantimonate

diphenyliodonium tetrakis(pentafluorophenyl)borate

bis-(4-methylphenyl)iodonium hexafluorophosphate

bis-(4-methylphenyl)iodonium hexafluoroantimonate

bis-(4-methylphenyl)iodonium tetrakis(pentafluorophenyl)borate

phenyl-4-methylphenyliodonium hexafluorophosphate

phenyl-4-methylphenyliodonium hexafluoroantimonate

phenyl-4-methylphenyliodonium tetrakis(pentafluorophenyl)borate

phenyl-4-methoxyphenyliodonium hexafluoroantimonate

phenyl-4-methoxyphenyliodonium tetrakis(pentafluorophenyl)borate

phenyl-3-nitrophenyliodonium hexafluorophenylantimonate

phenyl-3-nitrophenyliodonium tetrakis(pentafluorophenyl)borate

bis(4-tert-butylphenyl)iodonium hexafluoroantimonate

bis(4-tert-butylphenyl)iodonium tetrakis(pentafluorophenyl)borate

phenyl-4-diphenyliodoinium hexafluoroantimonate

dinaphthyliodonium hexafluorophosphate

dinaphthyliodonium hexafluoroantimonate

dinaphthyliodonium tetrakis(pentafluorophenyl)borate

bis(4-dodecylphenyl)iodonium hexafluoroantimonate

bis(4-dodecylphenyl) tetrakis(pentafluorophenyl)borate

4-methylphenyl-4-isopropylphenyliodonium hexafluoroantimonate

4-methylphenyl-4-isopropylphenyliodoniumtetrakis(pentafluorophenyl)borate

Reducing agents for carrying out the redox reaction for formation ofacids are organic or inorganic compounds or polymers which are capableof lowering the charge of the heteroatom within the diaryliodonium salt.Compounds which are worth mentioning are ascorbic acid and derivativesthereof, in particular the palmitate, oleate and acetate. Tin(II)compounds can also be employed, for example Sn²⁺ carboxylates, inparticular tin octoate, tin stearate, tin laurate, tin citrate, tinoxalate and tin benzoate. Among the organic compounds there may bementioned α-hydroxy compounds, for example ketones, in particularacyloins and benzoins. Also included are iron(II) compounds, for exampleferrocenes, FeBr₂ and FeCl₂, reducing sugars, such as glucose, fructoseand galactose, phenols, such as thiophenol, silanes and organosiloxanes.

Copper compounds are to be understood as meaning copper(I) andcopper(II) compounds, for example salts of carboxylic acids and mineralacids, such as CuBr, CuCl, Cu(II) benzoate, Cu(II) citrate, Cu(II)formate, Cu(II) acetate, Cu(II) stearate, Cu(II) oleate, Cu(II)carbonate, Cu(II) gluconate, Cu(II) naphthenoate or Cu(II)acetylacetonate.

Copper chelates such as are mentioned in Cotton and Wilkinson, AdvancedInorganic Chemistry, 3rd Edition, Interscience Publishers, New York,1972, pages 905 to 922 can also be used. Preferred copper chelates arethose which can be incorporated or dispersed in the cationicallypolymerizable material in a sufficient amount. Copper acetylacetonate,copper salicylate, CuI(C₆H₅)₃P, CuI(C₂H₅O)₃P, CuCl₂C₂H₈N₂,[(N—C₄H₉)₄N]₂CuCl₄ etc. are particularly suitable.

Alkyl halides which are suitable for the dehalogenation of alkyl halidesassisted by metal salts are described in “Makromol. Chem.” 178,2139-2140 (1977) and in “Die Makromolekulare Chemie” 156 (1972) 325-328.

Compounds of the type R₃C—X, wherein X represents a halogen, preferablyCl and Br, and R represents any desired substituted or unsubstitutedaliphatic or cycloaliphatic radical with a chain length of 1 to 15 Catoms, preferably 1 to 8 C atoms, or an aromatic radical substituted inany desired manner, are suitable in particular. Compounds with up tothree different substituents on the central C atom can also be used.

Metal salts are understood as meaning inorganic or organic metal saltswhich are capable of abstracting the halogen from the compounds of theabovementioned type. Possible salts are those such as AgBF₄, Ag SbF₆,AlCl₃, ZnCl₂ and also BF₃. Lewis acid compounds of the type M(III)X₃,M(II)X₂, M(V)X₅ and possible adducts thereof with AgX are generallysuitable. X here represents a halogen, preferably F, Cl or Br, and Mrepresents a metal from the main or sub-group in question, preferablyfrom main groups III and V, and in these preferably B, Al, Sb or As, andfrom sub-groups I, II, IVa and VIIIa, and in these preferably Cu, Ag,Zn, Fe, Co, Ni and Ti.

Diluents as flow improvers as constituent (C) are present in at leastone of the two components of the preparations according to theinvention. Diluents which are usually used as plasticizers canadvantageously be employed.

Typical representatives are the esters of phthalic acid, such asdi-2-ethylhexyl phthalate, or the esters of polybasic aliphatic acids,such as dioctyl adipate or acetyl tributylcitrate.

In addition, aliphatic and aromatic hydrocarbons with 6 to 30 C atomswhich can be branched or unbranched are very suitable. Typical examplesare polypropylene oils or polyisobutylene oils. Advantageously, aromatichydrocarbons such as polyphenylene compounds, dibenzyltoluene anddibenzylphenyl methane are used.

Polyester polyols which can be prepared for example by polycondensationfrom low-molecular polyols and polycarboxylic acids and/or theiranhydrides can also be used.

Typical representatives of this class are marketed by Hüls under thename Dynacoll. Preferably, polyester polyols whose molar masses arebetween 1000 and 5000 g/mol and hydroxyl equivalent masses of 500 to2000 are used.

Particularly preferably, polyester polyols as they can be obtainedthrough catalysed reactions of caprolactone with different startingalcohols can be used.

Typical representatives of this compound class are marketed by UCC underthe name Tone or by Daicel under the name Placcel.

Polycaprolactone triols with molar masses of 200 to 1000 g/mol andpolycaprolactone diols with molar masses of 300 to 2000 g/mol can beused.

Furthermore, polycarbonate diols with molar masses of 400 to 2000 g/moland the general structure

can be used as diluents, X and Y being able to be identical or differentand, independently of each other, mean alkylene, arylene, alkarylene,polyoxyalkylene and p can assume values between 1 and 50.

Furthermore, partly epoxidated polybutane diols can optionally be usedwhich represent homopolymerisates of butadiene, which are terminatedwith OH groups, have molar masses of 1000 to 5000 g/mol and possess ahigh content of double bonds, which, through epoxidation, can optionallybe partly converted to central aliphatic epoxide groups. Representativesof this compound class are marketed by Atochem under the name “Poly bd”.

Finally, polyether polyols of the general structure:

can also be used, m meaning an integer of 20 to 150, n an integer of 1to 5 and R hydrogen or C1-C4 alkyl.

Preferably, mixed polyether polyols which are composed of propyleneoxide units and/or ethylene oxide units and/or tetrahydrofurane units,are used.

Alkoxy-extended polyols such as for example ethoxylated Bisphenol A orpropoxylated trimethylol propane can also advantageously be used.

To adjust the properties, it can be expedient to use mixtures of polyolsof different average molar mass and different structure.

By modifiers are meant for example fillers. Fillers can be for examplequartz, quartz powder, ground or reactive glasses, fragmentpolymerisates, silica gels as well as pyrogenic silicic acid or theirgranules, customary in the dental field. But other fillers such as forexample finely-distributed metal or plastic powder, barium sulphate,titanium dioxide or in general finely-ground minerals are suitable. Forbetter incorporation into the polymer matrix, it can be advantageous tohydrophobize the fillers. Hydrophobizing agents are silanes, for exampleglycidyloxypropyltrimethoxysilane. The maximum particle size of theinorganic fillers is 100 μm, preferably 20 μm.

As further modifiers, such as dyes or thixotropic agents, the substancescustomary in the dental engineering field can be used.

The two components of the preparations according to the invention can bestored separately, for example in double-chamber cartridges, and bemixed internally before use by eduction via a static or dynamic mixer.Hand-mixing variants are also possible.

The ratio between the component containing no epoxy compounds and thecomponent containing epoxy compounds can be 1:10 to 1:1 and preferably1:5 to 1:2.

EXAMPLES

The invention is described in more detail below by examples from themodel material sector, which are in no case intended to limit the scopeof the invention. The substances used in the course of these examplescan be obtained from the following manufacturers:

Aerosil R 805 Degussa Aerosil R202 Degussa Celloxide 2021 P UCB CitrofolB1 Jungbunzlauer Dianol 265 Akzo Nobel Jarytherm DBT Elf Atochem Placcel305 Interorgana(Daiccel) Rhodorsil 2074 Rhone-Poulenc Silbond FW 100 ESTQuarzwerke Frechen Silbond FW 300 EST Quarzwerke Frechen Silbond FW 600EST Quarzwerke Frechen Titanium dioxide P 25 Degussa

The substance CEPK is a cycloaliphatic epoxy resin with four epoxygroups prepared in accordance with the instructions of DE-A-196 48 283.

The substance LM used as a stabilizer was prepared in accordance withDE-A-197 53 461, example 1.

The base pastes and catalyst pastes characterized in the followingexamples with the aid of their compositions were prepared in 3-fingerkneaders on a 100 g scale. After achieving a homogeneous state ofmixing, the pastes were evacuated and then introduced into 4:1double-chamber cartridges.

Comparison Example 1

Base paste Catalyst paste Celloxide 2021 P 49.899% Dianol 265 77.00%Silbond FW 600 49.000% Silbond FW 300 20.00% EST EST Aerosil R202 1.000%Aerosil R202 1.00% LM 0.101% Titanium dioxide P 1.00% 25 HSbF₆ 60% 1.00%

Example 1

Base paste Catalyst paste Silbond FW 100 46.979% Silbond FW 100 46.944%EST EST CEPK 16.992% Dianol 265 19.477% Silbond FW 600 15.993% SilbondFW 600 15.981% EST EST Celloxide 2021 P 8.996% Butyl lactate 8.490%Poly-THF 250 4.498% Rhodorsil 2074 5.528% Dianol 265 3.998% Aerosil R8051.498% Aerosil R805 1.500% Ascorbic acid 0.984% Copper 0.544% HSbF₆ 60%0.599% naphthenoate 8% in white spirit Titanium dioxide 0.500% Titaniumdioxide P 0.499% P25 25

Example 2

Base paste Catalyst paste Silbond FW 100 31.750% Silbond FW 100 62.500%EST EST Silbond FW 600 31.750% Dianol 265 13.065% EST CEPK 17.300% Butyllactate 8.500% Celloxide 2021 P 10.315% Poly-THF 250 6.915% Dianol 2654.570% Rhodorsil 2074 5.535% Poly-THF 250 2.418% Aerosil R805 1.500%Aerosil R805 1.500% Titanium dioxide P 1.000% 25 Copper 0.397% Ascorbicacid 0.985% dimethacrylate

Example 3

Base paste Catalyst paste Silbond FW 100 EST 47.845% Silbond FW 100 EST43.713% Silbond FW 600 EST 14.952% Placcel 305 31.009% CEPK 12.460%Silbond FW 600 EST 15.005% Celloxide 2021 P 12.460% Copper 4.272%tetrafluoroborate Placcel 305 4.485% Jarytherm DBT 4.001% Jarytherm DBT3.987% Aerosil R805 1.500% Diphenylmethyl 1.818% Titanium dioxide P 250.500% chloride Aerosil R805 1.495% Titanium dioxide P 25 0.498%

Example 4

Base paste Catalyst paste Silbond FW 100 EST 47.025% Silbond FW 10041.943% EST Silbond FW 600 EST 14.976% Dianol 265 18.475% CEPK 10.483%Silbond FW 600 14.980% EST Celloxide 2021 P 10.483% Placcel 305 10.985%Dianol 265 6.490% Iron(II) tetra- 6.068% fluoroborate Citrofol B1 5.990%Citrofol B1 4.993% Triphenylmethyl chloride 2.556% Aerosil R805 1.498%Aerosil R805 1.498% Tetrafluoroboric acid 0.559% 48% Titanium dioxide P25 0.499% Titanium dioxide P 0.499% 25

Example 5

Base paste Catalyst paste Silbond FW 100 EST 45.804% Silbond FW 10044.432% EST CEPK 16.589% Placcel 305 26.991% Silbond FW 600 EST 14.990%Silbond FW 600 14.996% EST Celloxide 2021 P 7.993% Jarytherm DBT 7.997%Jarytherm DBT 5.996% Zinc 3.584% tetrafluoroborate Placcel 305 4.497%Aerosil R805 1.500% Triphenylmethyl 2.132% Titanium dioxide P 0.500%chloride 25 Aerosil R805 1.499% Titanium dioxide P 25 0.500%

The comparison of the properties of the materials according to theinvention with commercially available products in table 1 clearly showsthat the materials offer advantages to the dental technician.

Millable after Flexural strength Can be mixed Material [min] [Mpa]automatically Comparison 30 105 ± 14 Yes example 1 Example 1 45 65 ± 6Yes Example 2 45 99 ± 7 Yes Example 3 30 62 ± 5 Yes Example 4 45 34 ± 3Yes Example 5 45 41 ± 1 Yes Comparison 30-60 16 ± 2 No example 2Comparison 360-480 43 ± 2 No example 3

In comparison example 1, in which only free acid was employed as theinitiator, the processing time of 60 seconds was too short. A super-hardgypsum of the Fujirock (GC) brand is used as comparison example 2, and aconventionally curing epoxy resin of the Blue Star type E (Girbach)brand is used as comparison example 3.

What is claimed is:
 1. Two-component preparation comprising components(I) and (II), wherein at least one component comprises epoxy compoundsand the preparation cures by cationic polymerization, initiated by Lewisand/or Brönsted acids, after mixing of the two components, thepreparation comprising the Lewis and/or Brönsted acids in the form ofprecursor compounds which are suitable for the formation of Lewis and/orBrönsted acids and are formed by chemical reaction after mixing of thetwo components.
 2. Preparation according to claim 1, characterized inthat the epoxy compounds and the compounds which are capable of theformation of Lewis and/or Brönsted acids and do not react with the epoxycompounds are present in component (I) and/or in component (II) in anydesired distribution.
 3. Preparation according to claim 1, characterizedin that it additionally comprises Lewis and/or Brönsted acids in freeform as part of that component which comprises no epoxy compounds. 4.Preparation according to claim 3, characterized in that the epoxycompounds are present in component (I), the Lewis and/or Brönsted acidsin free form are present in component (II) and the compounds which aresuitable for the formation of Lewis and/or Brönsted acids and do notreact with the epoxy compounds are present in component (I) and/or (II)in any desired distribution.
 5. Dental composition from preparationsaccording to one of claims 1 to 4, characterized in that they comprise,distributed over components (I) and (II), the constituents: (A) 10 to 80wt. % of epoxy compounds, (B) 0.01 to 20 wt. % of compounds which arecapable of the formation of Lewis and/or Brönsted acids, and optionallyfree Lewis and/or Brönsted acids, (C) 10 to 89.99 wt. % of diluents, (D)0 to 79.99 wt. % of modifiers, the wt. % data relating to the totalweight of the mixed preparations.
 6. Dental composition according toclaim 5, characterized in that cycloaliphatic epoxy compounds and/oraromatic epoxy compounds and/or aliphatic epoxy compounds are used asconstituent (A).
 7. Dental composition according to claim 5,characterized in that cycloaliphatic epoxy compounds with at least twoepoxy groups or cycloaliphatic epoxy compounds with at least four epoxygroups or cycloaliphatic epoxy compounds with two epoxy groups andcycloaliphatic epoxy compounds with at least four epoxy groups are usedas constituent (A).
 8. Dental composition according to claim 5,characterized in that the content of epoxy compounds with at least fourepoxy groups in the mixed preparations is 5 to 60 wt. %, preferably 5 to50 wt. %.
 9. Dental composition according to claim 5, characterized inthat it comprises compounds which are suitable for the formation ofBrönsted acids, and in that these are present in an amount such that theconcentration of the Brönsted acid optionally employed in free form is0.1 to 5 wt. %, based on the mixed dental composition.
 10. Dentalcomposition according to claim 9, characterized in that the Brönstedacids are produced by a redox reaction from bisaryliodonium salts, andthat free Brönsted acids are optionally additionally present.
 11. Dentalcomposition according to claim 10, characterized in that the freeBrönsted acids optionally additionally present and the Brönsted acidsproduced by redox reactions from bisaryliodonium salts are identical, orin that the free Brönsted acids optionally additionally present and theBrönsted acids produced by redox reactions from bisaryliodonium saltsare different.
 12. Dental composition according to claim 5,characterized in that the Brönsted acid or Lewis acid carbenium ions areproduced by reaction of alkyl or aryl or mixed alkyaryl halides withmetal salts after mixing of the two components.
 13. Dental compositionaccording to claim 12, characterized in that zinc, iron and/or coppersalts are employed as the metal salts.
 14. Dental composition accordingto claim 5, characterized in that the anion of the Brönsted acids ischosen from the group consisting of hexafluorophosphate,hexafluoroarsenate, hexafluoroarntimonate,tetrakis(pentafluorophenyl)borate and tetrafluoroborate.
 15. Dentalcomposition according to claim 5, characterized in that the ratiobetween the component comprising no epoxy compounds and the componentcomprising epoxy compounds 1:10 to 1:1, and preferably 1:5 to 1:2. 16.Process for mixing the dental composition according to claim 5,characterized in that mixing of the two components takes place bydynamic mixing processes or with the air of a static mixer mounted on adouble-chamber cartridge.
 17. A dental composition made by thepreparations according to any one of claims 1 to
 4. 18. A dentalcomposition which comprises epoxy compounds wherein said dentalcomposition cures by cationic polymerization initiated by a Lewis and/ora Brönsted acid and wherein the Lewis and/or the Brönsted acid areemployed in the form of precursor compounds which are suitable for theformation of the Lewis and/or the Brönsted acid and are formed bychemical reaction during or after mixing the dental composition. 19.Dental models, fillings, temporary crowns, temporary bridges or fixingcements made by the dental composition according to claim
 18. 20. Dentalmodels, fillings, temporary crowns or bridges of cement made by thedental composition according to claim 17.